One of the pathophysiological features in Buerger's disease, i.e. thromboangitis obliterans (TAO), is vasospastic phenomena. So autonomic reactivity was evaluated in 12 patients of Buerger's disease (1-6 years duration) and compared to age and sex matched controls (nonsmokers). Basal heart rate was significantly (P < 0.001) higher without any variation in blood pressure in TAO group compared to controls. Valsalva ratio (P < 0.01) and 30:15 ratio (P < 0.001) were increased without any effect on E:I ratio in TAO group versus controls. On head up tilt (HUT), there was significant (P < 0.001) fall in blood pressure in TAO group compared to controls. On cold pressure test (CPT), systolic blood pressure was reduced significantly (P < 0.01) in TAO group than that of controls, however, diastolic blood pressure showed no change in two groups. Responses indicate towards lower sympathetic reactivity in Buerger's patients.